No fuel pressure but Fass pump is working.

[Mopar1973Man]

Best I can say is have your ECM tested. Grab the rebuild list and pick one.

[int3man]

1 hour ago, Mopar1973Man said:

Best I can say is have your ECM tested. Grab the rebuild list and pick one.

Hi All,

               Not to question but can't he measure the input voltage to the ECM?  If it's not getting 12 volts.  Unplug the ECM and turn the key on and what voltage do you get?  12 V or 6.5V  Still 6.5V your problem is feeding the ECM.

 

Michael

[Mopar1973Man]

2 hours ago, int3man said:

Not to question but can't he measure the input voltage to the ECM?

 

ECM will not boot below 8 Volts.

[IBMobile]

4 hours ago, the7t7 said:

So I hooked a tester to the fuel system relay signal wire (#1 or 85 lead)

When you say fuel system relay is this the relay supplied by Fass for the lift pump or the fuel pump relay, in the PDC, for the VP44?

 

     RELAY TEMINALS 

old number     new number

   86                      1

   85                      2

   30                      3

   87a                    4

   87                      5

Most systems use terminal  #86 (1) to energize the relay solenoid and terminal #85 (2) for ground. 

                                 

 

[the7t7]

3 hours ago, IBMobile said:

When you say fuel system relay is this the relay supplied by Fass for the lift pump or the fuel pump relay, in the PDC, for the VP44?

I measured the voltage at the relay terminal in the pdc labeled “Fuel system relay”. I looked at the diagram on the relay and checked the voltage on terminals 85 and 86. 86 had continuity to ground so I assumed that 85 was the ecm signal wire. I’m assuming this relay is the injection pump relay because it’s the only one related to fuel in the pdc I could find. I had already measured the voltage on the lift pump trigger wire coming directly from the ecm earlier which was 6.5 volts. This is the wire pair that goes to the Fass relay. I swapped two other relays in this plug to check to see if it was the relay that was bad. Fass pump runs if I put 12 volts direct from battery to it (through relay plug terminal 87)

[Mopar1973Man]

PDC relay is the VP44. 

 

You need the relay for you lift pump. Typically elsewhere.

[Alterego]

@the7t7 dumb question I'm sure but have you checked All your grounds. In my recent adventure pulling all the engine wiring harnesses. The grounds are junk they are just bundled together and crimped in a metal clip then covered with sub par heat shrink. I ohmed mine out and replaced all of them with solder sleeves then added adhesive aviation quality environmental sleeves. @Mopar1973Man said the ecm wont boot under 8 volts. I would check your power and grounds to the ecm and see if you can correct it there. Dont give up. If you have a power probe you can induce voltage and check circuits that way, just be careful there are some circuits that use reference volt of 5 volts and putting 12volts to them is not good. Power probe makes a 5volt adapter for there system. 

Edited February 17, 2019 by Alterego
Changed some wording

[the7t7]

It’s probably a good idea for me to check the grounds just to be thorough. I had recently gotten both a new/reman ecm and pcm in an effort to get a Smarty with command module to work properly after having tested every wire between the pcm, ecm, and obd2 port. After getting new computers I still had the same smarty issues. My consolation for dumping so much money on computers is that at least I am starting fresh with new ones to match the mods and upgrades to my engine. Now I’m not so sure. After spending a couple months trying to sort out the smarty issue with experts on the the smarty support forum, I came to the conclusion that I had a really early 1998.5 24v that just wasn’t completely supported by smarty (which they would never admit). Both computers worked fine before I replaced them. It was just the only thing left to do. In the end, I switched to a Quadzilla setup which after switching from Dynomite injectors to DAP, worked fine until this issue.

 

What I don’t understand is why the ecm is putting out sub optimal voltages to both the vp44 relay and the Fass lift pump relay. I’ll check as many grounds as I can find and reach but I’m not holding my breath. A bad ground it would seem to me to either cause intermittent problems or complete failure.

Edited February 17, 2019 by the7t7

[Alterego]

@the7t7 if you have high resistance in one of your ground paths it will drop your voltage, and give you the condition you have now. There is a good article on here about the ground mod that fixes alot of issues. 

[int3man]

1 hour ago, the7t7 said:

It’s probably a good idea for me to check the grounds just to be thorough. I had recently gotten both a new/reman ecm and pcm in an effort to get a Smarty with command module to work properly after having tested every wire between the pcm, ecm, and obd2 port. After getting new computers I still had the same smarty issues. My consolation for dumping so much money on computers is that at least I am starting fresh with new ones to match the mods and upgrades to my engine. Now I’m not so sure. After spending a couple months trying to sort out the smarty issue with experts on the the smarty support forum, I came to the conclusion that I had a really early 1998.5 24v that just wasn’t completely supported by smarty (which they would never admit). Both computers worked fine before I replaced them. It was just the only thing left to do. In the end, I switched to a Quadzilla setup which after switching from Dynomite injectors to DAP, worked fine until this issue.

 

What I don’t understand is why the ecm is putting out sub optimal voltages to both the vp44 relay and the Fass lift pump relay. I’ll check as many grounds as I can find and reach but I’m not holding my breath. A bad ground it would seem to me to either cause intermittent problems or complete failure.

Hi the7t7,

                I have a 2001 Truck.  I discovered that I had a poor voltage connection to my MAP Sensor.  There was a Factory Splice connecting the Oil Pressure sensor and MAP sensor 5 volt wire.  I finally found it and cut it out.  I then measured the resistance through the splice, I had a 1,000 ohm resistance through this splice.  So I wouldn't trust a splice.  I have to dive back in for a broken wire.  At that point I'll treat the ECM Grounds to a rework as well.  Just my 2 cents worth.   That would help explain why none of the electronics fixed your issues.

 

Michael

Edited February 17, 2019 by int3man

[the7t7]

Thanks for the comments everyone! Looks like I will be feet up in the engine compartment today checking grounds and splices

[int3man]

Hi the7t7,

                 O.K.  So I looked at the schematic that Mike sent me and the splice I was after was between the Oil Pressure sensor and the MAP Sensor.  So I dropped the Starter motor and unstrung the wiring harness from the firewall and  the ECM and towards the front of the motor.  I was then able to feed the wiring harness out in front of the front axle and then I was able to strip the harness and trace the wires.  So I found my Splice was 12 - 14 inches in front of the ECM, the wire was long and double folded forward to take care of the excess wire.  I did see the splice for the ground going back to ground near the starter.

 

I was able to polish and clean that ground ring terminal having it laying in front of me.  Here is the factory splice, and the ECM forward where I found it.  Grounds should be ECM rear.  Trust me it's a lot easier to work on this crap laying on your side in front of the truck rather than standing on your head.  The harness is just held in with several clamps.

 

This was my solution, your mileage may vary, Good Luck!

Michael

Edited February 17, 2019 by int3man
Typo's

[the7t7]

Dang I wish I had seen this earlier. I spent the afternoon laying on top of the engine reworking those grounds (blk/wht). They probably aren’t the problem since they don’t ground the ecm but I thought I would do them anyway. I will be doing the Alt feed/ground mod tomorrow which I believe does ground the ecm. Removing the starter was a good idea.

[the7t7]

I have good power and grounds to the ECM. Less than 0.3 ohms through both power (R/wht) and ground wires (blk/tan). I did the alternator ground wire mod anyway and fused the blue wire. I’m sending my ecm back to ACS to check out. 

 

Maybe more evidence that I have a weird early 24v unless it’s specific to 98/99.  My wiring is different than what was described in the ground mod articles. The B+ lead for the alternator went down through the big bundle under the injection pump back to the starter and then up the fender well to the pdc. I just cut it back at those points so I wouldn’t have to undo the whole large bundle where I can’t reach it and then ran a new wire to the aux battery. I also had a large plastic block with the alternator ground, green and blue wires molded into it. I cut that off, elongated the wires and added new terminals. 

Edited February 20, 2019 by the7t7
Typos

[the7t7]

On 2/16/2019 at 6:12 AM, Mopar1973Man said:

 

Quadzilla Adrenaline, Edge Products, no. They do not leave a footprint. Smarty is a possible footprint but they claim it undetectable. 

 

I finaly got my ECM back from ACS and it was fried. They replaced it under warranty even though they determined I had a tuner which was nice of them because I didn’t say I had one. Here is the report:

 

Notes:your warranty has been completed (please note: your are a valued customer we have informed that shorts, tuner and no communication & tampering of our factory programming is not covered under warranty) we have covered all warranties & shipping which is not part of policy and procedure, this is our last warranty being issued. Unfortunately your module communication was killed from you trying to program injectors into the module & low voltage from trying to program the module and once recovered all data was corrupted and unable to save the module, they are very delicate units. Unfortunately you have voilated warranty policy by altering of our factory programming & are NO Longer covered under warranty,charges will apply should you need our assistance moving forward. How ever we stand behind our products and have sent you a completely different module programming has been done completely..

Our findings:

 ECM(engine control module).. unit was DOA (dead on arrival), based on recovery file from cummin they units communication was taken out by altering of our factory programming & low voltage from trying to program.. upon recovery data info was corrupt unit unable to save.

Prior to installing repaired unit:

a problem still lies in vehicle (it keeps taking out the injectors ). Battery & terminal must be changed.  Make sure all parts replaced are OEM (mopar) parts are a MUST! All Problem in truck must be tended to prior to installing repaired unit ( failing to do so will result in shorting out the unit and it will not be covered under warranty.) please refer to website for warranty coverage policy and procedures.

 

————————

Attached are the photos they sent.

 

As for the their report, they determined that the unit wasn’t getting enough voltage. However when I tested resistance on the supply leads and the grounds of the ecm they were fine. I had also replaced both batteries recently with AGM units. I guess I can power probe the ecm supply as Alterego says below but not sure what that means.

 

On 2/17/2019 at 7:09 AM, Alterego said:

@the7t7 dumb question I'm sure but have you checked All your grounds. In my recent adventure pulling all the engine wiring harnesses. The grounds are junk they are just bundled together and crimped in a metal clip then covered with sub par heat shrink. I ohmed mine out and replaced all of them with solder sleeves then added adhesive aviation quality environmental sleeves. @Mopar1973Man said the ecm wont boot under 8 volts. I would check your power and grounds to the ecm and see if you can correct it there. Dont give up. If you have a power probe you can induce voltage and check circuits that way, just be careful there are some circuits that use reference volt of 5 volts and putting 12volts to them is not good. Power probe makes a 5volt adapter for there system. 

 

Is this just putting 12v to the wires without the ecm hooked and checking voltage drop up or is there more to it?

 

They also recommended that I replace the Battery terminals. Mine don’t seem to be corroded or anything. Any suggestions here?

Edited March 13, 2019 by the7t7

[dripley]

Does the quad actually put any programming into the ECM or just intercept and send its own similar to the Comp. I guess there are several things that dont make sense to me. But I aint the brightest bulb in the pack on these kind of things.

[Dieselfuture]

I'm more than sure it intercepts the signal between ECM and vp44 modifies it and sends it on, fingers pretty quick if thing is pretty quick if you ask me.